Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1994-12-27
1996-09-10
Johnson, Rachel
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
25218218, 528 73, 528288, 528392, 525123, 525455, 560180, 526312, C08G 1862
Patent
active
055546870
DESCRIPTION:
BRIEF SUMMARY
The present application was filed under the provisions of USC 371 as the US National Phase of PCT application PCT/FR93/00630, filed Jun. 24, 1993.
BACKGROUND OF THE INVENTION
The present Invention relates to new heat-resistant high modulus materials, to compositions used for the manufacture thereof and to finished product parts which may be obtained from such materials Reaction-injection molding is a rapid polymerization process which is commonly used to produce polyurethanes and polyureas having elastomeric to rigid properties. This technology is used in the production of automobile parts, such as bumpers or fenders. In said process, two highly reactive streams of chemical compounds are intermixed under a high pressure, for example about 80 to 200 bars, in a mixing chamber having small dimensions where the streams are directly injected into each other. The mixed material Immediately runs into a mold where the chemical reaction continues and where the molded part is cross-linked. One of the streams contains a polyisocyanate, while the other flow contains a chain extender and a polymer, which has a high molecular weight and is reactive with isocyanate.
High modulus polymers obtained by the reaction-injection molding process can replace steel automobile panels, provided that they can withstand finishing operations on production lines where high temperatures prevail. A composite material is known from U.S. Pat. No. 4,880,872, which material is obtained by such a process from a first mixture of aromatic polyisocyanate and a cross-linking agent and from a second mixture comprising: containing at least one ethylenically unsaturated monomer, such as styrene, and at least one ethylenically unsaturated polymer, such as a polyester; molecular weight of between 190 and 3 000, and -C.sub.16 aliphatic diamines, C.sub.6 -C.sub.16 cycloaliphatic diamines and aromatic diamines, having at least one alkyl substituent in the ortho position of each amine group. and an increased resistance to heat, according to the particular measuring method described in the patent mentioned above.
In fact, the composite material described in that document has a number of disadvantages: on the one hand, the flexural modulus obtained is very low in comparison to that which may be obtained in respect of a similar material which does not contain polyoxyalkylene polyamine, as is shown in the comparative Example given below. On the other hand, when the resistance to heat of said material is determined not only by the method particular to said patent, but by the more conventional measurement of the heat distortion temperature, it is noted that said heat distortion temperature does not exceed about 50.degree. C., which is unsatisfactory for many applications of the product.
A technical problem to be overcome by the present invention is, thus, to provide a material which can be obtained in particular by the reaction-injection molding process and which combines, at one and the same time, a high flexural modulus, a high heat distortion temperature and a high impact resistance, a compromise which is not achieved by the teachings of U.S. Pat. No. 4,880,872 nor by the prior art.
On the other hand patent application FR-A-2,667,602 discloses a molding composition based on polyester-polyurethane, characterized in that it comprises a first soft phase of polyurea within a second more rigid phase of polyester-polyurethane formed by the reaction of: polymerization catalyst, and unsaturated monomer wherein are dissolved about 40 to 90% by weight of an unsaturated polyester-polyol, substantially free from water, comprising at least a dicarboxylic alkene group and having an acid number lower than 5, and (ii) a nitrogenated polyfunctional compound comprising at least two nitrogen atoms in each molecule, which, once reacted with component A, has a molecular weight sufficient for forming the first soft polyurea phase, groups of the nitrogenated compound is between about 3:1 and 100:1, the ratio of the active NCO groups to the active OH groups in the polyester-polyo
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Cray Valley S.A.
Johnson Rachel
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